ASoC: nau8325: new driver

The driver is for amplifiers NAU8325 of Nuvoton Technology Corporation.
The NAU8325 is a stereo high efficiency filter-free Class-D audio
amplifier, which is capable of driving a 4ohm load with up to 3W output
power.

Signed-off-by: Seven Lee <wtli@nuvoton.com>
Link: https://msgid.link/r/20240327075755.3410381-3-wtli@nuvoton.com
Signed-off-by: Mark Brown <broonie@kernel.org>